Reductive cross-coupling reactions of unsaturated compounds Abstract Organic molecules play an important role in a number of research areas relevant to human health, including biology, medicine, and drug development. One of the goals of synthetic organic chemistry is to facilitate discovery in these fields by providing access to organic molecules of increasing complexity and variety, and by expanding our ability to efficiently manipulate their structure and their properties. A critical part of the efforts toward this goal is the development of new organic transformations. The goal of the research described in this proposal is the development of the following two classes of transformations: 1) Syn-selective reductive cross- coupling reactions of alkynes. 2) Anti-selective cross-coupling reactions of terminal alkynes. Once successfully developed, these transformations will provide a more efficient alternative to the cross-coupling reactions of functionalized alkenes and will provide access to classes of compounds that are difficult to access using available methods. As a result, the proposed transformations have a potential to increase the efficiency of the drug development process, decrease its environmental impact and economic cost, and thus contribute to further improvements in human health.